The present application claims priority to Japanese Application No. P11-204037 filed Jul. 19, 1999; which application is incorporated herein by reference to the extent permitted by law.
The present invention relates to an optical device, and particularly to an optical device such as a display device having at least an image optical display function or a two-dimensional optical operating device.
Recently, the demand for display devices has become stronger as man-machine interfaces. In general, the display device is classified into a spontaneous light emission type and a light receiving type. Examples of the spontaneous light type may include a CRT (Cathode Ray Tube), a PDP (Plasma Display Panel), an ELD (Electroluminescence Display), a VFD (Vacuum Fluorescent Display), and an LED (Light Emitting Diode). Examples of the light receiving type may include an LCD (Liquid Crystal Display), and an ECD (Electrochromic Display). The performances of these displays have been improved by development of electronics, and the quality and cost thereof have already reached the period of maturity or they are anticipated to reach the period of maturity sooner or later.
The conventional display using electronics requires electrodes for applying an electric field and a current on a display screen, and accordingly, if it is intended to enlarge the display panel, an increase in electric resistance due to the electrodes and wiring thereof inevitably occurs. In other words, the display panel, that is, the screen size of the display is limited for suppressing the increase in electric resistance due to the electrodes and wiring thereof. In addition, since the display is generally made from a hard material, the degree of freedom in shape of the display is small, and consequently, it is difficult to variously change the shape of the display and make compact the size of the display.
An object of the present invention is to provide an optical device capable of ensuring a display function of forming an image having a high quality, typically, a high contrast, enlarging the size of the screen, and performing collective light emission operation, by controlling light not with the aid of an electric field and current but with the aid of excitation of light intensity.
The present inventor believes that a technology called xe2x80x9cphotonicsxe2x80x9d will surpass the above-described conventional electronics in the 21th century. While electronics control electrons via an electric field, photonics controls light without the use of any electric field.
The vibrational field of light functioning as electromagnetic radiation has a strong interaction with charged particles in a molecule, that is, electrons and protons in a molecule. With respect to protons, a nucleus packed with protons and neutrons is regarded as stationary even if it interacts with light because the nucleus has a large mass. In other words, the interaction between light and a nucleus is negligible from the interaction between light and a substance. Meanwhile, an electron having a mass being as small as about {fraction (1/2000)} that of a proton can sufficiently follow the vibrational field of light vibrating at a high frequency. Accordingly, the interaction between light and a substance may be regarded as the interaction between light and electrons in a molecule. A large number of electrons are present in a molecule. Of these electrons, those located on the outer orbit constrained weakly by a nucleus are easy to interact with light.
The absorption of light is a transition from a state S0 to Sn in the interaction between light and electrons in a molecule, which terminates in the order of femtosecond. Such an instable state (Frank-Condon state) does not continue so long, and a nucleus having a large mass and positively charged is shifted in its coordinate to cause the relaxation. The time scale of occurrence of this relaxation is in the order of picosecond. A state S1, which is a relatively stable excitation state, is generated along with relaxation of the nucleus. The life of the S1 state is in the order of nanosecond, which time substantially governs the steps associated with the excitation state caused by absorption of light.
The present invention, particularly, provides a new, useful display using the photonics which will get ahead of the electronics in the 21th century. Concretely, according to a first aspect of the present invention, there is provided an optical device including: a first optical waveguide (or optical fiber); a second optical waveguide (or optical fiber) crossing to the first optical waveguide; and an element to be excited by light rays waveguided in the first and second optical waveguides, the element being disposed at a crossing portion at which the first and second optical waveguides cross each other; wherein the optical device has at least an optical display function.
According to the optical device of the present invention, since the elements to be excited are excited not with the aid of the conventional electronics but with the aid of the photonics, more concretely, the elements disposed at the crossing portions of the first and second optical waveguides are excited by light rays waveguided in the first and second optical waveguides, to selectively extract and cutoff the light rays from the elements. As a result, since an image can be displayed on a display screen only by optical excitation, without use of an electric field and a current on the display screen (except for a semiconductor laser and the like), it is possible to realize an optical display function having a high quality, for example, a high contract, and also realize an optical operation function. Further, since electrodes which have obstructed the enlargement of a panel are not provided, there is no limitation to a screen size of an optical waveguide (or optical fiber) display, so that the display screen can be formed into an arbitrary size, for example, into a large size. In addition, since the display can be made from a soft material, it can be formed into an arbitrary shape.
In the above optical device, preferably, the element to be excited is one kind or a combination of two kinds or more selected from a group consisting of an element capable of modulating its refractive index by optical excitation, an element capable of modulating its distribution of refractive index by optical excitation, an element capable of modulating its light emission intensity by optical excitation, an element capable of modulating its coloring density by optical excitation, and element capable of modulating its dielectric constant by optical excitation, an element capable of modulating its magnetic permeability by optical excitation, a liquid crystal element capable of changing its orientation state of liquid crystal by optical excitation, and an element allowing light scattering by optical excitation, and a light ray is selectively extracted or cutoff from the crossing portion by the optical excitation, to perform optical display and/or optical operation.
In the above optical device, preferably, the first optical waveguide is configured as a plurality of first optical waveguides (or optical fibers) and the second optical waveguide is configured as a plurality of second optical waveguides (or optical fibers); and light sources are directly or indirectly optically coupled to the pluralities of optical waveguides in such a manner that when the light sources are directly optically coupled to the optical waveguides, the optical waveguides and the light sources are provided on one-to-one correspondence; and when the light sources are indirectly optically coupled to the optical waveguides, the light sources are connected to at least one of the optical waveguides via optical waveguide members.
According to a second aspect of the present invention, there is provided an optical device including: a plurality of first optical waveguides (or optical fibers) arranged in the horizontal direction; a plurality of second optical waveguides (or optical fibers) arranged in the direction perpendicular or nearly perpendicular to the first optical waveguides, the second optical waveguides being not optically coupled to the first optical waveguides at crossing portions at which the first and second optical waveguides (or optical fibers) cross each other; and elements to be excited by light rays waveguided in the first and second optical waveguides, the elements being arranged at the crossing portions; wherein the elements to be excited are selected for each line by intensities of light rays in the first optical waveguides (or optical fibers) functioning as horizontal waveguides (or optical fibers); and light rays in the second optical waveguides (or optical fibers) functioning as vertical waveguides (or optical fibers) are modulated in intensity on the basis of data signals, and the data signal light rays whose intensities have been modulated are extracted to the outside via the selected elements to be excited.
According to a third aspect of the present invention, there is provided an optical device including: a plurality of first optical waveguides (or optical fibers) arranged in the horizontal direction; a plurality of second optical waveguides (or optical fibers) arranged on the same plane as that on which the first optical waveguides (or optical fibers) are arranged, the second optical waveguides (or optical fibers) being perpendicular or nearly perpendicular to the first optical waveguides (or optical fibers); and elements to be excited by light rays waveguided (or optical fibers) in the first and second optical waveguides (or optical fibers), the elements being arranged at crossing portions at which the first and second optical waveguides (or optical fibers) cross each other; wherein the elements to be excited are selected for each line by intensities of light rays in the first optical waveguides (or optical fibers) functioning as horizontal waveguides (or optical fibers); and light rays in the second waveguides functioning as vertical waveguides (or optical fibers) are modulated in intensity on the basis of data signals, and the data signal light rays whose intensities have been modulated are extracted to the outside via the selected elements to be excited.
In the above optical device, preferably, the element to be excited is provided with means capable of controlling the temperature of the element to be excited or means capable of applying a high frequency electric field to the element to be excited. With this configuration, in particular, when the element is configured as a liquid crystal device, the reversal of polarization of light crystal can be uniformly generated by increasing the temperature of the liquid crystal or applying a high frequency magnetic field to the liquid crystal.